What Is a Network Switch? Definition, Types, and Selection Guide
·2 min read·251 words
A network switch connects devices within the same local area network (LAN) by forwarding Ethernet frames based on MAC addresses. Unlike a hub, which broadcasts everything, a switch learns MAC addresses and forwards traffic only to the destination port. It is essential to every enterprise network.
How It Works
- MAC learning: learns the source MAC address from each incoming frame
- Forwarding: checks the MAC table to determine the destination port
- Flooding: if the destination MAC address is unknown, forwards the frame through all ports except the source port
- Aging: MAC entries are removed after 300s of inactivity by default
Types
- Unmanaged: plug-and-play, with no configuration required
- Managed: CLI/GUI, VLAN, QoS, SNMP
- L2: MAC-based forwarding
- L3 (multilayer): adds IP routing
- PoE / PoE+ / PoE++: power delivery over Ethernet
- Modular: chassis with interchangeable line cards
- Stackable: multiple switches managed as one
Key Specifications
- Number of ports (8, 16, 24, 48)
- Speed (1G, 10G, 25G, 100G, 400G)
- PoE budget (e.g., 370W, 740W, 1440W)
- Switching capacity (Gbps)
- Forwarding rate (Mpps)
- MAC table (8K, 32K, 128K)
- Jumbo frame support
Leading Brands
- Cisco Catalyst: campus networking leader
- Cisco Nexus: data center
- HPE Aruba CX: a strong Cisco competitor
- Juniper EX: campus + DC
- FortiSwitch: FortiGate integration
- Arista 7000: high-performance data center networking
- Meraki MS: cloud-managed
Use Cases
- Access layer: connecting endpoints
- Distribution: aggregation and routing
- Core: high-speed transport
- ToR (Top-of-Rack): data center servers
- Spine: data center backbone
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